1. Field of the Invention
The present invention relates to a differential gear and, more particularly, to a simple structure of high-performance differential gear.
2. Description of the Related Art
The transmission system of a motor vehicle is coupled between the motor and the wheels to provide a proper speed reducing ratio and a differential effect between the left and right wheels. For example, when the rear-wheel drive drives the motor vehicle to turn to the right, the revolving speed of the rear left wheel must be faster than the rear right wheel, forming a big radius of gyration and a small radius of gyration disposed in parallel to achieve the turning.
Various differential gears have been disclosed for use in motor vehicles. However, conventional differential gears are commonly comprised of a big number of gears. Due to complicated structure, conventional differential gears may fail to function easily, and much energy may be lost during friction among gears. Further, the maintenance work of conventional differential gears is also complicated.
Therefore, it is desirable to provide a differential gear that eliminates the aforesaid drawbacks.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a differential gear, which uses a simple planet gear set to provide a differential effect, achieving the advantage of simple structure. It is another object of the present invention to provide a differential gear, which uses less number of parts to achieve a high transmission effect.
To achieve these and other objects of the present invention, the differential gear is to be driven by a driving device to rotate a first driven member and a second driven member, comprising: a main gear wheel to be driven by the driving gear to rotate on an imaginary axis, the main gear wheel having a first side and a second side opposite to the first side; a first output device, the first output device comprising a first sun gear pivoted to the first side of the main gear wheel for free rotation on the imaginary axis, and a first output shaft extended axially outwardly from the center of the first sun gear along the imaginary axis and adapted to rotate the first driven member; a second output device, the second output device comprising a second sun gear pivoted to the second side of the main gear wheel for free rotation on the imaginary axis, and a second output shaft extended axially outwardly from the center of the second sun gear along the imaginary axis and adapted to rotate the second driven member; and a first planet gear set, the first planet gear set comprising a first planet gear pivoted to the first side of the main gear wheel and meshed with the first sun gear, a second planet gear pivoted to the first side of the main gear wheel and meshed with the first planet gear, and a third planet gear pivoted to the second side of the main gear wheel and meshed with the second sun gear for synchronous rotation with the second planet gear in direction same as the second planet gear, the number of teeth of the second planet gear being less than the first and the third planet gear.